U.S. patent number 8,511,392 [Application Number 13/483,209] was granted by the patent office on 2013-08-20 for downhole swivel sub.
This patent grant is currently assigned to Tercel Oilfield Products UK Limited. The grantee listed for this patent is James Bain, Paul Howlett. Invention is credited to James Bain, Paul Howlett.
United States Patent |
8,511,392 |
Howlett , et al. |
August 20, 2013 |
Downhole swivel sub
Abstract
The present invention provides a swivel sub for connection in a
work string between a workstring and a downhole apparatus. The
swivel sub includes a first substantially cylindrical body,
including a sleeve portion having one or more teeth and a second
substantially cylindrical body being partially located within the
sleeve portion. The bodies are arranged to rotate relative to each
other. The swivel sub also includes a sliding sleeve, having one or
more teeth arranged mutually engage with the first teeth is axially
moveable between disengaged and engaged positions, in one
embodiment by a pressure differential being created in the sub.
Further, the present invention provides methods for of running the
tool, with particular application to setting and hanging of liners
and screens.
Inventors: |
Howlett; Paul (Aberdeen,
GB), Bain; James (Angus, GB) |
Applicant: |
Name |
City |
State |
Country |
Type |
Howlett; Paul
Bain; James |
Aberdeen
Angus |
N/A
N/A |
GB
GB |
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Assignee: |
Tercel Oilfield Products UK
Limited (Aberdeen, GB)
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Family
ID: |
34630734 |
Appl.
No.: |
13/483,209 |
Filed: |
May 30, 2012 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20120234559 A1 |
Sep 20, 2012 |
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Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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11911049 |
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8191639 |
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PCT/GB2006/001396 |
Apr 18, 2006 |
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Foreign Application Priority Data
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Apr 15, 2005 [GB] |
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0507639.3 |
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Current U.S.
Class: |
166/381; 166/237;
192/69.9 |
Current CPC
Class: |
E21B
17/05 (20130101) |
Current International
Class: |
E21B
23/04 (20060101) |
Field of
Search: |
;166/117.7,237,240,242.1,381,383 ;192/69.9,69.91 ;175/106,320
;464/18,20,21 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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2381806 |
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May 2003 |
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GB |
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2378197 |
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Jun 2003 |
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GB |
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WO 93/10326 |
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May 1993 |
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WO |
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Primary Examiner: Bagnell; David
Assistant Examiner: Michener; Blake
Attorney, Agent or Firm: Sughrue Mion, PLLC
Parent Case Text
CROSS REFERENCE TO RELATED APPLICATIONS
This application is a Continuation Application of U.S. application
Ser. No. 11/911,049 filed May 13, 2008, which is a National Stage
of International Application No. PCT/GB2006/001396 filed on Apr.
18, 2006, claiming priority based on British Patent Application No.
0507639.3, filed Apr. 15, 2005, the contents of all of which are
incorporated herein by reference in their entirety.
Claims
The invention claimed is:
1. A swivel sub for connection in a work string between a
workstring and a downhole apparatus, the sub comprising a first
substantially cylindrical body, including a sleeve portion having
one or more first teeth arranged thereon; a second substantially
cylindrical body being partially located within the sleeve portion
and the bodies being arranged to rotate relative to each other; a
sliding sleeve, including one or more second teeth arranged
thereon, to mutually engage with the first teeth; the sliding
sleeve being axially moveable between a first position wherein the
first and second teeth are disengaged and there is an overlap
between the sleeve portion and the sliding sleeve, and a second
position wherein the first and second teeth are engaged; wherein
the first and second bodies include central bores therethrough,
such that the sub has a central bore running axially therethrough,
and the sliding sleeve is directly exposed to a first fluid
pressure from the central bore of the sub and directly exposed to a
second fluid pressure outside the sub; and wherein the sliding
sleeve is moved by virtue of a pressure differential between the
first and second pressures.
2. The swivel sub as claimed in claim 1 wherein the first
cylindrical body is a top sub, including means for connecting the
top sub to a workstring.
3. The swivel sub as claimed in claim 1 wherein the second
cylindrical body is an inner mandrel including means for connecting
the inner mandrel, at a lower end, to a downhole apparatus.
4. The swivel sub as claimed in claim 1 wherein the sub includes at
least one shear pin which connects the sliding sleeve to the second
cylindrical body.
5. The swivel sub as claimed in claim 1 wherein the sliding sleeve
includes at least one locking dog.
6. The swivel sub as claimed in claim 5 wherein the locking dog is
adapted to engage the sliding sleeve with the second cylindrical
body to lock the sub in either of the first or second
positions.
7. The swivel sub as claimed in claim 1 wherein the sub is
initially set in the first position, wherein the sliding sleeve is
held to the second cylindrical body with the first and second teeth
disengaged.
8. The swivel sub as claimed in claim 1 wherein a drop ball seat is
located within the sub, in order to provide means for creating the
pressure differential in the sub.
9. The swivel sub as claimed in claim 1 further comprising biasing
means for biasing the sliding sleeve toward the first or the second
position.
10. The swivel sub as claimed in claim 9 wherein the biasing means
is a spring.
11. The swivel sub as claimed in claim 1 wherein the sub
incorporates an index sleeve.
12. The swivel sub as claimed in claim 1, further comprising a drop
ball seat located in the second cylindrical body for creating the
pressure differential within the sub.
13. The swivel sub as claimed in claim 1, further comprising a
retrievable plug and a plug profile within the sub for receiving
the plug and creating the pressure differential within the sub.
14. The swivel sub as claimed in claim 1, wherein the sub is
initially set in the second position, wherein the first and second
teeth are engaged.
15. A method of running a downhole apparatus into a wellbore, the
method comprising the steps of: (a) locating a swivel sub as
claimed in claim 1 between a workstring and a downhole apparatus;
(b) running the workstring into the wellbore while rotating the
workstring; (c) creating the pressure differential in the swivel
sub to switch the sub between a first position, in which the
workstring rotates relative to the downhole apparatus and a second
position in which the workstring and at least a portion of the
downhole apparatus rotate together.
16. The method as claimed in claim 15 comprising the additional
step of rotating the workstring with the swivel sub in the first
position such that the workstring rotates relative to the downhole
apparatus.
17. The method as claimed in claim 15 comprising the additional
step of rotating the workstring with the swivel sub in its second
position such that the workstring and at least a portion of the
downhole apparatus rotate together.
18. The method as claimed in claim 15, further including the step
of locking the sub in the second position.
19. The method as claimed in claim 15 wherein step (c) is repeated
so that the sub is cycled between the first and second
positions.
20. The method as claimed in claim 15 wherein the downhole
apparatus comprises a running or setting tool.
21. The method as claimed in claim 20 wherein the portion which
rotates with the workstring is the running or setting tool.
22. The method as claimed in claim 20 wherein the downhole
apparatus comprises a running or setting tool for a liner or
screen.
23. A method of running a downhole apparatus into a wellbore, the
method comprising the steps of: locating a swivel sub as claimed in
claim 1 between a workstring and a downhole apparatus; (b) rotating
the workstring with the swivel sub in a first position, such that
the workstring rotates relative to the downhole apparatus; (c)
running the workstring into the wellbore while rotating the
workstring; (d) creating the pressure differential in the swivel
sub to switch the sub into a second position, such that the
workstring and at least a portion of the downhole apparatus rotate
together.
24. The method as claimed in claim 23 further including the step of
rotating the workstring and the at least a portion of the downhole
apparatus.
25. The method as claimed in claim 23 further including the step of
creating a further pressure differential to relocate the sub into
the first position and rotating the workstring relative to the
downhole apparatus.
26. A swivel sub for connection in a work string between a
drill-pipe string and a screen or liner assembly, the sub
comprising a first substantially cylindrical body, including a
sleeve portion having one or more first teeth arranged on a surface
thereof; a second substantially cylindrical body being partially
located within the sleeve portion and the bodies being arranged to
rotate relative to each other; a sliding sleeve, including one or
more second teeth arranged on a surface thereof, to mutually engage
with the first teeth; the sliding sleeve being axially moveable
between a first position wherein the first and second teeth are
disengaged and there is an overlap between the sleeve portion and
the sliding sleeve, and a second position wherein the first and
second teeth are engaged; wherein the first and second bodies
include central bores therethrough, such that the sub has a central
bore running axially therethrough, and the sliding sleeve is
directly exposed to a first fluid pressure from the central bore of
the sub and directly exposed to a second fluid pressure outside the
sub; and wherein the sliding sleeve is moved by virtue of a
pressure differential between the first and second pressures.
Description
The present invention relates to downhole tools for use in the oil
and gas industry and, in particular, to a swivel sub suitable for
use when running delicate screens or liners into a wellbore, or in
directional drilling applications.
During completion of a oil or gas well, sand control screens or
liners are located in the wellbore. Typically the screens and
liners are lowered into the wellbore on a workstring, but there is
often insufficient workstring down weight available to the driller
to put the screens into the well without rotating the string to
break the friction. Applying too much downhole weight can
over-compress the pipe below, thereby causing damage. It is
advantageous to rotate the workstring attached to the screens or
liners when inserting in high angle/ERD (extended reach drilling)
or tortuous wells due to the fact that the associated drag of the
friction is reduced in the workstring, making it easier to observe
and apply the necessary measured down weight to aid getting sand
screens or liners to the planned depth. However, it is often not
desirable to rotate the screens or liners (perhaps with delicate
accessories) for fear of damage. For example, if the screen or
liner sticks, buckling can occur as a result of the applied
torque.
In directional drilling applications, using downhole drilling
motors or rotary steerable tools it will often be necessary to
selectively engage or disengage the main drill string with drill
bit to allow rotation independent of the main drill string at
times, and rotation with the drill string at others.
U.S. Pat. No. 5,394,938 describes a gravel pack screen wherein a
fluid permeable base pipe has a screen jacket rotatably mounted
thereon, so that the base pipe or drill-pipe string can be rotated
without imparting torque to the screen jacket. Such an arrangement
advantageously prevents torque being applied to the screen, but has
the disadvantage that for certain applications it is useful to be
able to selectively impart full rotation to the whole drill-pipe
string, including the screens and liners. For instance, it may be
desirable to have an ability to free a screen from a running tool
by releasing the running tool from the screen and rotating the
running tool, to prevent an unnecessary upward movement of the
screen during deployment.
U.S. Pat. No. 5,323,852 discloses an auger gravel pack screen
connected to a drill-pipe string which includes a torque limiting
device to limit the maximum torque exerted on the screen. While
this arrangement prevents damage to the screen from the over
application of torque, the device does not provide any selective
application of torque, as may be required for the release of
running tools, etc.
U.S. Pat. No. 6,244,345 describes a lockable swivel apparatus
located above the rotary table, which allows an operator to
selectively rotate the drill string while a wireline can be
manipulated below. One disadvantage of this swivel apparatus is
that in order to unlock or disengage the swivel, so that the parts
can be relatively rotated, weight must be set down on the drill
string. This would not be desirable in the use of sand screens or
liners, as the act of setting down weight on the sand screen or
liner may cause it to buckle and become damaged.
U.S. Pat. No. 6,516,878 describes a tension swivel sub used for
cutting and removing sections of a wellbore casing. A compression
spring maintains a spear located below a cutter into rotational
engagement with the string, and the spear is set against the casing
below the cutter. Tension is applied to overcome the compression
spring and disengage the spear from the string, so that the string
above the spear can be rotated. One disadvantage of these tools is
that they cannot be used on run in, as the drill-pipe string below
the sub must be held in place to disengage the drill-pipe string
and allow selective rotation of the cutter above.
It is an object of the invention to provide a swivel sub that
overcomes at least one drawback or disadvantage of prior art swivel
subs.
It is an object of at least one embodiment the present invention to
provide a swivel sub which allows the rotation of a drill-pipe
string above the sub to be selectively transmitted through the sub
to downhole apparatus, such as a screen, liner assembly, or drill
bit below.
It is a further object of at least one embodiment of the present
invention to provide a swivel sub wherein relative rotation between
the drill-pipe string above the sub and downhole apparatus below
the sub, such as a screen, liner assembly or drill bit, can be
achieved without compression or tension at the sub.
It is a further object of at least one aspect of the invention to
provide a downhole swivel sub that meets the objects above.
Additional aims and objects of the invention will become apparent
from the following description.
According to a first aspect of the present invention, there is
provided a swivel sub for connection in a work string between a
workstring and a downhole apparatus, the sub comprising a first
substantially cylindrical body, including a sleeve portion having
one or more first teeth arranged thereon; a second substantially
cylindrical body being partially located within the sleeve portion
and the bodies being arranged to rotate relative to each other; a
sliding sleeve, including one or more second teeth arranged
thereon, to mutually engage with the first teeth; the sliding
sleeve being axially moveable between a first position, wherein the
first and second teeth are disengaged and a second position,
wherein the first and second teeth are engaged; and means to engage
the sliding sleeve with the second cylindrical body.
The sliding sleeve may be operable to be engaged with the second
cylindrical body, or may be keyed with the second cylindrical
body.
Thus, with the sliding sleeve locked to the second body, the sub
may be arranged so that the teeth are locked in either the engaged
or disengaged position.
Preferably, the sliding sleeve is moved by virtue of a pressure
differential in the sub. The pressure differential may be created
by dropping a ball into a ball seat of a downhole apparatus, such
as a screen, liner assembly, or drill bit located below the
sub.
Alternatively, the sliding sleeve may be operated by a hydraulic
system. Optionally, the sliding sleeve may be moved by a mechanical
system.
In a first embodiment, the first cylindrical body is a top sub,
including means for connecting the top sub to a workstring. The
second cylindrical body may be an inner mandrel including means for
connecting the inner mandrel, at a lower end, to a downhole
apparatus. The downhole apparatus may be apparatus for running or
hanging a liner or screen. Alternatively, the downhole apparatus is
directional drilling apparatus.
Preferably, the first and second bodies include central bores
therethrough, such that the sub has a central bore running axially
therethrough. This arrangement allows wireline and other tools to
be located through the sub, and also allows for circulation fluids,
etc., through the sub and the drill-pipe string, if desired.
Preferably a bearing sleeve is located between the first and second
bodies to provide smooth rotation relative to each other.
Preferably, the sub includes at least one shear pin which connects
the sliding sleeve to the second cylindrical body.
More preferably, the sliding sleeve includes at least one locking
dog. In this way, an initial pressure differential will cause the
shear pin to shear and the sliding sleeve will move, such that the
first and second teeth move axially with respect to each other.
The locking dog can then engage the sliding sleeve with the second
cylindrical body to lock the sub in either of the first or second
positions.
In a preferred embodiment, the sub is initially set in the first
position, wherein the sliding sleeve is held to the second
cylindrical body with the first and second teeth disengaged. In
this arrangement, the second cylindrical body can rotate with
respect to the first cylindrical body. If the first cylindrical
body is connected to a drill-pipe string, this arrangement allows
the drill-pipe string to be rotated while apparatus attached to the
second cylindrical body will be held stationary. By the application
of differential pressure, the shear pin may shear and the sliding
sleeve will move axially over the second body until the locking dog
engages the sliding sleeve in a second position. The second
position has the first and second teeth engaged, and thus rotation
of the drill-pipe string and the first cylindrical body will cause
the second cylindrical body to rotate with the first cylindrical
body.
Optionally, a drop ball seat may be located within the sub, in
order to provide means for creating a pressure differential in the
sub.
Preferably, a spring is located between the first cylindrical body
and the sliding sleeve. In this way, the sleeve can be biased
toward the first or the second position.
Advantageously, the sliding sleeve may incorporate an index sleeve.
In this way, a pin and groove arrangement can allow the sliding
sleeve to selectively rotate around the second body, and move
axially so that the sub can be selectively engaged or disengaged
any number of times.
According to a second aspect of the present invention, there is
provided a method of running a downhole apparatus into a wellbore,
the method comprising the steps of: (a) locating a swivel sub
between a workstring and a downhole apparatus; (b) running the
workstring into the wellbore while rotating the workstring; (c)
creating a pressure differential in the swivel sub to switch the
sub between a first position, in which the workstring rotates
relative to the downhole apparatus and a second position in which
the workstring and at least a portion of the downhole apparatus
rotate together.
The method may comprise the additional steps of rotating the
workstring with the swivel sub in the first position such that the
workstring rotates relative to the downhole apparatus.
The method may comprise the additional step of rotating the
workstring with the swivel sub in its second position such that the
workstring and at least a portion of the downhole apparatus rotate
together.
The method may include the step of dropping a ball through the
workstring to land on a ball seat and create the pressure
differential.
The method may further include the step of locking the sub in the
second position.
The method may further include the step of creating a further
pressure differential to relocate the sub into the first position
and rotating the workstring relative to the downhole apparatus.
The downhole apparatus may comprise a running or setting tool.
Preferably, the portion which rotates with the workstring is the
running or setting tool.
In one embodiment, the downhole apparatus comprises a running or
setting tool for a liner or screen. Alternatively, the downhole
apparatus comprises directional drilling equipment.
According to a third aspect of the invention, there is provided a
method of running a downhole apparatus into a wellbore, the method
comprising the steps of: (a) locating a swivel sub between a
workstring and a downhole apparatus; (b) running the workstring
into the wellbore while rotating the workstring; (c) creating a
pressure differential in the swivel sub to switch the sub between a
first position, in which the workstring rotates relative to the
downhole apparatus and a second position in which the workstring
and at least a portion of the downhole apparatus rotate
together.
The method may comprise the additional step of rotating the
workstring with the swivel sub in the first position such that the
workstring rotates relative to the downhole apparatus.
The method may comprise the additional step of rotating the
workstring with the swivel sub in its second position such that the
workstring and at least a portion of the downhole apparatus rotate
together.
The method may include the step of dropping a ball through the
drill-pipe string in order to create the pressure differential.
Further, the method may include the step of creating a further
differential pressure to switch the sub back to the first position
and rotating the drill-pipe string and downhole apparatus
together.
Preferably, the steps can be repeated any number of times, so that
the sub may be cycled between the first and second positions.
According to a fourth aspect of the invention there is provided a
method of running downhole apparatus into a wellbore, the method
comprising the steps of: (a) locating a swivel sub between a
workstring and the downhole apparatus; (b) rotating the workstring
with the swivel sub in an engaged position, such that the
workstring rotates with the downhole apparatus; (c) running the
apparatus on the workstring into a wellbore, while rotating the
workstring and the apparatus; (d) creating a pressure differential
in the swivel sub, such that the sub switches to a disengaged
position, such that the workstring can be rotated relative to the
downhole apparatus.
The method may comprise the additional step of rotating the
workstring relative to the downhole apparatus.
The method may comprise the additional steps of creating a further
differential pressure to switch the sub back to the engaged
position, and; rotating the workstring and downhole apparatus
together.
According to a fifth aspect of the present invention, there is
provided a swivel sub for connection in a work string between a
drill-pipe string and a screen or liner assembly, the sub
comprising a first substantially cylindrical body, including a
sleeve portion having one or more first teeth arranged on a surface
thereof; a second substantially cylindrical body being partially
located within the sleeve portion and the bodies being arranged to
rotate relative to each other; a sliding sleeve, including one or
more second teeth arranged on a surface thereof, to mutually engage
with the first teeth; the sliding sleeve being axially moveable
between a first position, wherein the first and second teeth are
disengaged and a second position, wherein the first and second
teeth are engaged; and means to lock the sliding sleeve to the
second cylindrical body.
According to a sixth aspect of the invention there is provided a
method of running a screen or liner into a wellbore, the method
comprising the steps: (a) locating a swivel sub between a
drill-pipe string and a liner or screen assembly; (b) rotating the
drill-pipe string with the swivel sub in a first position, such
that the drill-pipe string rotates relative to the assembly; (c)
running the drill-pipe string into the wellbore while rotating the
drill-pipe string; (d) creating a pressure differential in the
swivel sub to switch the sub into a second position, such that the
drill-pipe string and at least a portion of the assembly rotate
together; and (e) rotating the drill-pipe string and the portion of
the assembly.
According to a seventh aspect of the present invention, there is
provided a method of running downhole apparatus into a wellbore,
the method comprising: (a) locating a swivel sub between a
drill-pipe string and the downhole apparatus; (b) rotating the
drill-pipe string with the swivel sub in a first position, such
that the drill-pipe string rotates with the downhole apparatus; (c)
running the apparatus on the drill-pipe string into a wellbore,
while rotating the drill-pipe string and the apparatus; (d)
creating a pressure differential in the swivel sub, such that the
sub switches to a second position, such that the drill-pipe string
can be rotated relative to the downhole apparatus; and (e) rotating
the drill-pipe string relative to the downhole apparatus.
Preferred embodiments of the fifth to seventh aspects of the
invention may include features of the embodiments of the first to
fourth aspects of the invention.
Embodiments of the present invention will now be described by way
of example only, with reference to the following drawings, of
which:
FIG. 1 is a cross-sectional view through a swivel sub according to
a first embodiment of the present invention, in an unlocked
configuration;
FIG. 2 is a cross-sectional view through the sub of FIG. 1 in a
second, locked configuration;
FIG. 3 is a sectional view through the Line A-A of FIG. 2; and
FIG. 4 is a schematic view of a swivel sub according a further
embodiment of the present invention.
Reference is initially made to FIG. 1 of the drawings, which
illustrates a swivel sub, generally indicated by reference numeral
10, according to the first embodiment of the present invention. Sub
10 comprises a first cylindrical body 12 having at an upper end 14,
a box section 16 for connecting the body 12 to a drill-pipe string
(not shown). The body 12 includes a bore 18 therethrough and at a
lower end 20 there is provided a sleeve 22 extending from the body
12. Located within the sleeve 22 is a bearing sleeve 24 which
includes bearings 26a,b to provide a rotational coupling to
anything placed adjacent to the bearing sleeve 24.
Located within the bearing sleeve 24 and thus rotationally coupled
to it, is an inner mandrel 28 Inner mandrel 28 is a cylindrical
body having a central bore 30 located therethrough. At an upper end
32, distal to the bearing sleeve 24, is a pin section 34 for
connecting the sub to a downhole apparatus (not shown).
Attached to the sleeve 22 is a locking sleeve 36 which may form
part thereof. The locking sleeve 36 abuts an outer surface 38 of
the mandrel 28. Locking sleeve 36 is preferably screwed to the
sleeve 22 and has at an upper end 40 a narrowed portion 42 which
has, on its outer surface 44, six teeth 46a-f, as illustrated in
FIG. 3.
Located on the outer surface 38 of the mandrel 28 is a sliding
sleeve 48. The sliding sleeve 48 is arranged to travel
longitudinally on the inner mandrel 28. Its passage is restricted
by an abutment face 50 on the mandrel 28 and by engagement with the
teeth 46 on the locking sleeve 36. At an upper end 52 of the
sliding sleeve, arranged on an inner surface 54 thereof, are
located six teeth 56a-f, as illustrated in FIG. 3. Teeth 46, 56 are
sized so that they can engage with each other when axially brought
together.
Located around the sliding sleeve 48 are six shear pins 58. The
shear pins 58 are equidistantly spaced around the sleeve 48,
passing through apertures in the sleeve 48 into the inner mandrel
28. Thus, the sliding sleeve 48 is fixed to the inner mandrel
28.
In a first configuration, as shown in FIG. 1, the shear pins 58 fix
the sliding sleeve 48 to the mandrel 28. The sliding sleeve 48 is
located against the abutment face 50. The teeth 46, 56 are
disengaged with the upper end 52 of sleeve 48 being clear of the
teeth 46 on the locking sleeve 36 though there is still provided a
small overlap to assist in positioning the sleeves on the sub 10.
Also located on the sleeve 48 is a locking dog 60. This is a sprung
pin which is biased towards the inner mandrel 28. In this
embodiment, the dog 60 is compressed.
Reference is now made to FIG. 3 of the drawings, which illustrates
the sub 10 of FIG. 1, in a second configuration. In FIG. 3, shear
pins 58 have been sheared and the sliding sleeve 48 has been moved
up so that the teeth 46, 56 are completely engaged. The locking dog
60 is now located over a recess 62 on the inner mandrel 28. The dog
60 expands to locate a pin into the recess 62. With the pin located
in the recess 62, the sliding sleeve 48 is prevented from movement.
The locking sleeve 36, through engagement with the sliding sleeve
48, is now locked to the inner mandrel 28.
In use, sub 10 is connected to a drill-pipe string via the box
section 16. A liner or screen is attached via a liner hanging tool
or running tool onto the pin section 34 at the lower end 32 of the
sub 10. The sliding sleeve 48 is arranged in the configuration
shown in FIG. 1, that is the sleeve is pulled back against the
abutment face 50 and the shear pins 58 are mounted through the
sleeve 48 into the inner mandrel 28. In this configuration the sub
is unlocked and the teeth 46, 56 are clear of each other and
disengaged. The inner mandrel 28 is now only connected to the top
sub 10 via the bearing sleeve 24. In this way, the body 12 and the
mandrel 28 can rotate independently of each other.
When run in a wellbore, the drill-pipe string at the upper end 14
of the sub 10 can be rotated, while the liner connected to the
inner mandrel 28 can remain stationary. No torque will be imparted
onto the liner, as it is all borne by the bearing sleeve 24.
Further rotation of the drill-pipe string above the sub is achieved
without tension or compression on the sub. This means that once the
screen or liner is at total depth (TD), the drill string can
continue to be rotated during circulation to aid in hole
displacement, and cuttings or debris removal without fear of
imparting rotation or torque below.
If rotation of the liner hanger or setting tool is required, a
differential pressure is induced within the sub 10. This can be
done by dropping a ball from the surface of the wellbore through
the bores 18 and 30 of the sub, and into a ball seat. The ball seat
may be mounted in the inner mandrel 28 or, alternatively, it may be
located in the liner hanging tool or running tool mounted on the
pin 34 of the inner mandrel 28. On passing a ball into the bore 30,
fluid can be circulated through the bore 30 to induce a pressure
build up within the sub 10, pressure outside the sub on the sliding
sleeve 48 will induce movement in the sleeve 48. Sufficient force
of the movement will break the shear pins 58, allowing the sleeve
48 to move.
Sleeve 48 will move towards the upper end 14 of the sub 10. As the
sleeve 48 moves, the teeth 56 pass between the teeth 46 on the
locking sleeve 36. The engagement of the teeth 46,56 causes the
sleeves 36, 48 to couple until the locking pin 60 reaches the
recess 62, whereupon movement of the sliding sleeve 48 is then
prevented. In this position, teeth 46, 56 are fully engaged and the
sliding sleeve 48 is locked to the inner mandrel 28. Torque now
imparted from the drill-pipe string will cause rotation of the body
12 and the locking sleeve 36. By virtue of the engagement of the
teeth 46,56, the sliding sleeve 48 will be forced to rotate with
the body 12. As the sliding sleeve 48 is locked to the inner
mandrel 28, the inner mandrel will now also rotate with the body
12, thus the entire sub 10 will rotate with the drill string.
This feature can be considered an emergency device that can be used
to help screen deployment running tools that perhaps will not
release easily. Having an ability to rotate the running tools to
free them from the running assembly, may prevent the unnecessary
upward movement of the screens or liner once deployed. The lock-up
feature could also be necessary if hydraulically tools were
required to be released by their emergency release features, i.e.,
through left-hand rotation, as is the case for some liner hanger
tools used for screen deployments.
In the embodiment shown, a predetermined differential pressure at
the sub of around 2,500 psi is required to disengage the sliding
sleeve and cause movement into the locked position. The
differential pressure can be achieved by pushing up against a ball
on a shearable ball seat. It could also be applied by running a
retrievable plug to a profile at the bottom of the sub 10. The
retrievable plug would be inserted through the bores 18 and 30 of
the sub 10.
Reference is now made to FIG. 4 of the drawings which shows a
swivel sub generally indicated by reference numeral 110, according
to a further embodiment of the present invention. Like parts to
those of the swivel sub 10 shown in FIGS. 1 to 3, have been given
the same reference numeral with the addition of 100. The embodiment
in FIG. 4 is similar to the swivel sub 10 of FIGS. 1 to 3, but
comprises two additional features. The first of these is the
incorporation of a spring 70 located between the sleeves 136 and
148. A first end 72 of spring 70 is located within a recess 74 in
the upper face 152 of the sliding sleeve 148. An opposing end 76 of
the spring 70 is located in a recess 78 within a portion 80 of a
locking sleeve 136, behind the teeth 146.
In use, when the differential pressure increases sufficiently to
shear the shear pin 158, the sleeve 148 will move over the sleeve
136 for the teeth 146, 156 to engage. As the sleeve 148 moves, the
spring 70 is compressed. As long as the differential pressure is
maintained, the sleeve 148 will remain over the teeth 146 and the
sub 110 will rotate in its entirety. Release of the differential
pressure will cause the sleeve 148 to drop so that it falls back to
the abutment face 150. On reaching the abutment face 150, the sub
110 is now disengaged and the body 112 connected to the drill-pipe
string can be rotated relative to the inner mandrel 128.
It will be appreciate that merely by varying the differential
pressure across the sub 110, the sub 110 can be moved from the
engaged to disengaged position any number of times. The sub 110
therefore has an advantage over the sub 10, in that it can be used
repeatedly. However, the sub 10 has the advantage that it can be
locked in either position.
A further feature which may be added to the sub 110 is the
incorporation of an index sleeve 82. The index sleeve 82 forms a
portion of the inner mandrel 128 and comprises a continuous groove
86 machined circumferentially around the outer surface 138 of the
mandrel 128. Located on the inner surface 154 of the sliding sleeve
148 is a pin 84. Although only one pin is illustrated, it will be
appreciated that a number of pins may be used to increase the
stability of the sub 110 and distribute the loading on the sub 110
in use. Pin 84 locates in the groove 86. Groove 86 is a typical
J-slot arrangement which is circumferentially arranged around the
inner mandrel 128.
In use, the pin 84 is initially located in a first slot and by
varying the differential pressure on the sub 110 and via the bias
on the spring 70, the pin 84 is moved around the groove 86. It can
be appreciated that the pin 84 may be arranged on the sleeve 48,
while the groove 86 is arranged on the inner mandrel 128. The
arrangement of the J-slots would then be repositioned
accordingly.
The principal advantage of the present invention is that it
provides a swivel sub which allows a workstring to be rotated above
the sub, while a downhole apparatus, such as a screen, liner
assembly, or drill bit below the sub is not affected by the
rotation or torque.
A further advantage of the present invention is that it provides a
swivel sub, wherein the rotational coupling can be selectively
deployed so that, if necessary, the torque can be imparted through
the sub.
A yet further advantage of the present invention is that it
provides a swivel sub in which relative rotation between the
workstring above and downhole apparatus, such as a screen, liner
assembly, or drill bit below the sub, can be achieved without
compression or tension at the sub.
It will be appreciated that while the terms `upper` and `lower`
together with `top` and `bottom` have been used within this
specification, they are relative terms and the sub could find equal
application in deviated or horizontal wellbores.
Various modifications may be made to the invention herein described
without departing from the scope thereof. For instance, although
the change in differential pressure has been described by the
action of a ball landing on a shearable ball seat or by running of
a retrievable plug to a profile at the bottom of the sub, the
movement of the sliding sleeve can also be effected by the
application of hydraulics on the surface, or indeed by other
mechanical means. Additionally, the embodiments described show a
sub wherein the drill-pipe string can rotate relative to apparatus
connected at the base of the sub during run-in, the sub could
equally be set such that the sub is locked to provide through
rotation during run-in, and then unlocked in a position in the
wellbore. This feature may be suitable for the operation of
hydraulic tools located at the base of the sub.
* * * * *